Radio range system



May 3l, 1949. H, w|| K|E E1- AL 2,471,470

RADIO RANGE SYSTEM Original Filed Nov. 23, 1942 2 Sheets-Sheet 1 Arma/VIYS 31, 1949, H. wnLKlE Erm..

RADIO RANGE SYSTEM Original Filed NOV. 23, 1942 @scf/vf? 2 Sheets-Sheet 2 tamed n, 1949 2,471,410

2,471,470 mimo RANGE SYSTEM .Hai-ryl Wilkie, Dayton, and Francis L. Moseley, Osborn, Ohio Continuation if-application serial No. 466.55m, November 23, 1942. This application February i, i943, serial Nia-474,332 d claims. (ci. 34a-107) (Granted under the ect ci Merch s, ists, cs

amended April 30, `1928: 370 0. G. 157) The invention described herein may be manugovernmental purposes, withoutthe payment to us ofany royalty thereon.

-airingv the bearing line between thel transmitting factured and used by or for the Government for 2 station and the receiver cater is energized.

By radiating the signals of diierent patterns in three equi-angularlyspaced directions from 'This invention relates to omni-directional 5 vthe center of the radiating station, -in suchfmanradio range systems. ner as to setup radiating fields having .cardioidal One object of our invention is to provide an characteristics, the received signals of the sevomni-directional radio range system, wherein a 'eral patterns 4.may be detected and isolated and standard radio receiver may be utilized with athen re-conrbined to measure the respective'amsimple auxiliary indicating equipment, to estab l0 plitndes and thereby establish the bearing '1111 lislliu bearingitline with respect to a radio range toglie iransmiiilg Systm. ib1 of own pos ion. e ransm g sys em compr ses a s a e Another object ofthis invention is to provide radio transmitter, with an antenna System so enaradio range system whereby a traveling vehicle, ergized and controlled that a number of known such as a truck or an aircraft, mayl establish its eld strength patterns may be radiated by suitline of bearing to a known radiating station, with able switching .,controls a standard radio receiver and a simple economical i:hIn ociie' o iegsligllalishbthe diiierenit patterns of auxiliary indicator. I. e ra a e s s a 1 ase or carr er' requency Other objects of our invention are; may be modulated by a numberof different .fre- 1' To mvide an ommdirectional range system 20 quencies to establish the number of energy impulses having different patterns that aredesired. wherein both the transmitting equipment and The received signal of each pattern is segre leggg equipment employed are rela' f gated from the output of the standard receiver by means of a suitable tuned filter. Each im- 2' egu lailifs indication of the 25, pulse after having been thus segregated is prefer- 3. To-provide a system in which simple and small nceagltgxlidsygleglvlepin antenna structures may be employed; in which eating .device I no effort or special attention isrequired on the -The transmitted signals of he three different part of the receiving station operator in order patterns,derived from the modulation of the carto obtain bearing; in which the entire indicatn in rier frequency by the three different modulating g equipment will be about the size of a v frequencies, energize the respective eld windings standard radio compass indicator, in which no of the Selsyn receiver to establish respective field adjustments will be required while the system t is in, intensities which vary according to the angular n use, other than ordinary receiver tuning v v distance ofthe bearing line of the receiver from and volume control setting and the transmite the axes ofthe ca-rdioid field set up by the radi ting equipment may .be made portable; and in ation of the signals of that particular vpattern which the only labor for setting up the system Since the patterns ofthe respective signals will on vgfutlgeb 505.24m .orientation and the turning j be radiated in diiferent directions around the pp l' l 40 vcircle of the center of the radiating system, the The principle of operation of this invention vSelsyn'indicator willnalways orient itself in a utilizes, vand is basedupon, an automatic land sub direction "along the axisof the strongestiieldor stantially instantaneous comparison of the amresultant of the elds, which will-be aligned with x plitudes received from a number or known radiv the vbearing line between the'- receiver and the Y ation patterns from the same transmitting range. vradiating system. l The signalsare radiated sequentiallyin'equal suc- The manner in whichthe system is set up, and cessive-'time intervals from the transmittingrangeV operates,is` illustrated 'in the accompanying Aandvare'remotely detected on thejvehicleY-andcondrawings, in which: y fverte'dto direct current impulses, andare dis- Figure 1 is a schematic view illustrating the pose'd to -establish co-operating vmagnetic `elds 50 disposition of the axes of the radiated elds of the correspondingin intensity to the respective-amplirespective sets of modulated signals of different l tudes'of the received signals., The resultingmagfrequencies; I n'etic fields establish the locationofthe magnetic v Figure-2 is a schematic vand, block diagramof v axis, vvwhich-will then orient itself in a directionthe radio range system including both thetrans- 'mitting andreceiving parts of the system.

through which the indi-` Figure 3 is a block diagram of the transmitting system which forms part of my invention.

Figure 4 is a plan diagram of the transmitting e radio antennas and their reflectors.

As shown in Figure 1, the transmitting part of the system is -arranged and controlled with suitable equipment to set up three radiation fields having cardioid characteristics with the center axes of the respective fields equi-angularly spaced 120 degrees apart.

For convenience of reference, the fields will be as represented by the cardioids I, 2, and 3, respectively related to the directional axes 4, 5, and 6. The center point 1 of the field will represent the center of the radio range from which the signals are radiated.

The apparatus and equipment that are employed in the system, as a whole, are illustrated generally in the block diagram of Figure 3, in which the transmitting equipment particularly is illustratively identified, in brief, as an oscillator I0, three modulators II, I2 and I3, respectively, a switching device I4, and radiating antenna units I5, I6, and I1, respectively.

The receiving equipment of the system is shown as comprising, generally, a single receiving antenna 20, a receiver 2|, whose output is delivered to three filters and attenuators 22, 23, and 24, respectively. The segregated received energy impulses from the filters are respectively rectified by double wave rectiers 25, 28, and 21, and then supplied from these rectifiers to the three equally spac'ed windings 23, 29, and 30 of a Selsyn receiver unit 3| that also embodies a free iioating indicator or magnet bar 32. That bar assumes a position along the axis of the resultant magnetic eld Aof the three windings of the Selsyn unit.

Referring back to the transmitting part of the system, the modulators I I, I2, and I3 are operated at three different modulating frequencies to provide three dissimilar impulses that have to be separated at the receiver. The modulated signais of the three groups are transmitted for equal intervals of time and are in turn respectively supplied by suitable switching equipment, indicated by the block I4, to each of the respective radiating antennas I5, I B, and I1.

These ,antennas I5, I 6, and I1 are physically disposed to supply both the directional characteristics, and to establish the cardioid field characteristic for the corresponding impulse transmitted l by each antenna unit. 4

In that manner, all of the energy impulses of the same modulating frequency, and of the same pattern are radiated in the same direction. The respective elds are disposed around the circle having the radio range at the center, and these elds provide a coordinated radiation pattern in which the result will be radiantly oriented, and therefore will always be a bearing line passing through the center of the radiation system.

At the receiver, the. several impulses are disposed to be segregated and physically `disposed in the corresponding manner in which the impulses are transmitted so that the benefit of the directional eifect may be procured.

Thus, where the modulated impulses are transmitted in the sequence of the modulators II, I2, and I3, the corresponding detected impulses of the modulating frequencies passed through the filters 22, 23, and 24 should be supplied to the windings of the Selsyn unit 3l, so that the rectified impulses will energize the windings 28, 29, and 3U in the same sequence with the windings physicallydisposed in the same relative position as the field patterns in Figure 1, corresponding to the radiations from the transmitting antenna units I5, I6, and I1, respectively.

The resultant field set up by the windings 28, 29 and 30 will be oriented with its axis in the direction of the bearing line between the receiver and the transmitting radio range. The indicator bar 32 will align itself along that axis and will serve to indicate the direction of the bearing lines.

Figure 4 illustrates an antenna system for producing the eld pattern of Figure 1. Three antennas I5, I6, and I1 located at the vertices of an equilateral triangle. Three reflectors I5s, I6s and I'Is are used to reflect the wave and create the desired directional effect. It is understood that while three antennas are shown, the basic principle of our invention is not limited thereto as any number designed to create a rotating field will operate.

If the radio receiving system of Figure 2 is located on an airplane or balloon directly above the center of the antenna system, the apparatus will be a true Selsyn system and the indicator 32 will rotate synchronously withthe frequency of the system. If the indicator is directly above the station it may be rotated to any fixed position by energizing any one or two of the antennas I5, I6, and I1. However, the main use for this invention is to guide an airplane to an airport and when this is done, the antenna I5, I6, and Il are intermittently and successively energized by the three modulating frequencies. Henc'e a rotating field is set up around the antennas and the airport. The equipment of Figure 2 is located on the aircraft and the Selsyn bar 32 always indicates the correct direction toward the airport.

This application is a continuation of our prior copending application entitled Radio range system, filed November 23, 1942, Serial No. 466,5591/2, now abandoned.

We claim:

1. An omni-directional radio range system, comprising a radiating system of Aequi-angularly spaced radiating units; a source of carrier frequency; means for modulating the carrier source to derive three dissimilar energy Wave impulses; means for transmitting those respective impulses sequentially to the respective radiating units during successive equal time intervals, thereby to establish a, rotating radiation field with directional characteristics; means for receiving and segregating the wave impulses, rectifying them, and setting up in the samesequence, adjacent direct mutual manual magnetic fields equi-angularly spaced; and means for indicating the location of the magnetic axis of the mutual field.

2. The method of operating an omni-directional range system, which consists in generating an alternating voltage of constant frequency; modulating that voltage separately by three voltages of different frequencies to derive three modulated wave impulses of dissimilar pattern; radiating the impulses in fixed sequence and in successive tane intervals to establish equi-angularly spaced elds having cardioid characteristics; remotely detecting, and segregating, and rectifying the impulses; and supplying those pulses inthe same sequence as their radiation, to equally spaced windings of a Selsyn receiver Whose rotor is free fioating to orient itself along the magnetic axis of the resultant mutual field of the Selsyn Windings.

.'3. An omni-directional range system comprising a radiating assembly including means for radiating a train of wave impulses in xed sequence and in successive time intervals, means to establish equi-angularly spaced elds having cardioid characteristics, said impulses having dissimilar patterns established by three diierent modulating frequencies, and means for detecting the impulses and converting them to equally spaced mutual magnetic forces to establish a re- -sultant magnetic axis of the common field; and means for indicating the relative location of the resultant magnetic axis so established.

4. An omni-directional range system cornprising a source of fixed carrier frequency; means for modulating the carrier to derive a, plurality .of dissimilar Wave impulses in regular and recurring sequence at equally spaced time intervals; means for radiating the impulses in the same sequence and time intervals and in equi-angularly spaced'directions, thereby to establish a rotating radiation eld with directional characteristics;

' and remote means for detecting the radiated impulses, rectifying them, and setting up therewith in the same sequence, adjacent equi-angularly distributed direct mutual magnetic flux elds in proportion to the strength of the respective received impulses, to establish a resultant magnetic -eld whose -axis will be oriented in the direction of the strongest received impulse of the sequence.

5. An omni-directional radio range system, comprising a radiating system of equi-angularly spaced radiating units; a source of carrierfrequency; means for modulating the carrier source to derive a plurality of dissimilar energy wave impulses; means for transmitting those respective impulses sequentally to the respective radiating units during successive equal time intervals there-l by to establish a rotating radiation fleld with directional characteristics; means for receiving and segregating the Wave impulses, rectifying them, and setting up in the same sequence, adjacent direct mutual magnetic elds equi-angularly spaced; and means for indicating the location of the resultant magnetic axis of the mutual eld.

HARRY WILKIE. FRANCIS L. MOSELE'Y.

REFERENCES CITED The following references are of record in the le of this patent:

Luck July '1, 1942 

